Hello,
To implement this in the DTB, the only changes that you could do is with the frequency of your SPI module and sometimes the SPI driver is disabled in the DTB, you may need to activate it also.
Regarding how to implement the zigbee communication, depends a lot on your end application. However, how you are implementing your communication through SPI, you will create the zigbee communication through SPI commands. Please see the below web-page, there is an example of how to use the Linux SPI driver.
http://linux-sunxi.org/SPIdev
Best Regards,
Diego.